Lennox ML196DF045XE36B User manual

Page 1 ©2021 Lennox Industries Inc.
Litho U.S.A.
Corp. 1910-L7
02/2021 ML196DFE
Service Literature
ML196DFE SERIES UNITS
ML196DFE series units are high-efficiency gas fur
naces manufactured with Lennox DuralokPlustalumi
nized steel clamshell-type heat exchangers, with a stainless
steel condensing coil. ML196DFE units are available in
heating input capacities of 44,000 to 110,000 Btuh and
cooling applications from 2 through 5 tons. Refer to Product
Specifications for proper sizing.
Units are factory equipped for use with natural gas. A kit is
available for conversion to LP/Propane operation. All
ML196DFE units are equipped with a hot surface ignition
system. The gas valve is redundant to assure safety
shut-off as required by C.S.A.
The heat exchanger, burners and manifold assembly can be
removed for inspection and service. The maintenance section
gives a detailed description on how this is done.
All specifications are subject to change. Procedures outlined
in this manual are presented as a recommendation only
and do not supersede or replace local or state codes.
WARNING
Electric shock hazard. Can cause injury
or death. Before attempting to perform
any service or maintenance, turn the
electrical power to unit OFF at discon
nect switch(es). Unit may have multiple
power supplies.
Table of Contents
Specifications 2.................................
Optional Accessories 3..........................
Blower Performance Data 4......................
I-Unit Components 5............................
II Placement and Installation 19....................
III-Start-Up 39...................................
IV-Heating System Service Checks 40..............
V-Typical Operating Conditions 44.................
VI-Maintenance 45...............................
VII-Wiring and Sequence of Operation 48...........
VIII-Troubleshooting 49...........................
WARNING
Improper installation, adjustment, alteration, service
or maintenance can cause property damage, person
al injury or loss of life. Installation and service must
be performed by a licensed professional HVAC in
staller (or equivalent), service agency or the gas sup
plier.
CAUTION
As with any mechanical equipment, contact with
sharp sheet metal edges can result in personal in
jury. Take care while handling this equipment and
wear gloves and protective clothing.

Page 2
SPECIFICATIONS
Gas
Heating
Performance
Model No. ML196DF045XE36B ML196DF070XE48B ML196DF090XE48C ML196DF110XE60C
1AFUE 96% 96% 96% 96%
Input - Btuh 44,000 66,000 88,000 110,000
Output - Btuh 42,000 64,000 85,000 106,000
Temperature rise range - °F 30 - 60 35 - 65 50 - 80 40 - 70
Gas Manifold Pressure (in. w.g.)
Nat. Gas / LPG/Propane 3.5 / 10 3.5 / 10 3.5 / 10 3.5 / 10
High static - in. w.g. 0.5 0.5 0.5 0.5
Connections
in.
Intake / Exhaust Pipe (PVC) 2 / 2 2 / 2 2 / 2 2 / 2
Gas pipe size IPS 1/2 1/2 1/2 1/2
Condensate Drain Trap (PVC pipe) - i.d. 3/4 3/4 3/4 3/4
with furnished 90° street elbow 3/4 slip x 3/4 Mipt 3/4 slip x 3/4 Mipt 3/4 slip x 3/4 Mipt 3/4 slip x 3/4 Mipt
with eld supplied (PVC coupling) - o.d. 3/4 slip x 3/4 MPT 3/4 slip x 3/4 MPT 3/4 slip x 3/4 MPT 3/4 slip x 3/4 MPT
Indoor
Blower
Wheel nom. diameter x width - in. 10 x 8 11-1/2 x 10 10 x 10 11 x 11
Motor Type DC Brushless DC Brushless DC Brushless DC Brushless
Motor output - hp 1/2 3/4 3/4 1
Tons of add-on cooling 1.5 - 3 2 - 4 2 - 4 3 - 5
Air Volume Range - cfm 505 - 1455 525 - 1720 860 - 1760 1010 - 3115
Electrical
Data
Voltage 120 volts - 60 hertz - 1 phase
Blower motor full load amps 6.8 8.4 8.4 10.9
Maximum overcurrent protection 15 15 15 15
Shipping Data lbs. - 1 package 126 139 154 XXX
NOTE - Filters and provisions for mounting are not furnished and must be eld provided.
1 Annual Fuel Utilization E󰀩ciency based on DOE test procedures and according to FTC labeling regulations. Isolated combustion system rating for non-weatherized furnaces.

Page 3
OPTIONAL ACCESSORIES
“B” Width Models “C” Width Models
CABINET ACCESSORIES
Downow Combustible Flooring Base 11M60 11M61
CONDENSATE DRAIN KITS
Condensate Drain Heat Cable 6 ft. 26K68 26K68
24 ft. 26K69 26K69
Crawl Space Vent Drain Kit US 51W18 51W18
Canada 15Z70 15Z70
CONTROLS
Blower Relay Kit (for two-stage outdoor units) 85W66 85W66
iComfort®M30 Smart Wi-Fi Thermostat 15Z69 15Z69
Remote Outdoor Temperature Sensor X2658 X2658
Twinning Kit 16W72 16W72
DOWNFLOW FILTER KITS
1 Downow Filter Cabinet 51W07 51W08
No. and Size of lter - in. (2) 16 x 20 x 1 (2) 16 x 20 x 1
NIGHT SERVICE KIT
Night Service Kit 84W48 84W48

Page 4
ML196DF070XE48B PERFORMANCE (Less Filter)
External
Static
Pressure
in. w.g.
Air Volume / Watts at Various Blower Speeds
High Medium-High Medium Medium-Low Low
cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts
0.00 1720 510 1545 355 1340 235 1240 190 1020 95
0.10 1700 530 1505 360 1310 245 1195 200 955 110
0.20 1675 545 1465 370 1275 255 1155 205 895 115
0.30 1640 555 1420 380 1230 270 1120 215 835 125
0.40 1600 565 1380 395 1180 280 1060 225 785 135
0.50 1560 570 1340 400 1140 290 1015 235 715 145
0.60 1500 565 1300 420 1095 305 965 245 640 150
0.70 N/A N/A 1255 430 1040 315 910 255 585 160
0.80 N/A N/A 1215 445 990 320 865 265 525 170
ML196DF045XE36B PERFORMANCE (Less Filter)
External
Static
Pressure
in. w.g.
Air Volume / Watts at Various Blower Speeds
High Medium-High Medium Medium-Low Low
cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts
0.00 1455 370 1275 255 1175 190 920 90 865 85
0.10 1425 375 1250 260 1145 200 885 100 830 90
0.20 1395 380 1225 265 1115 210 850 110 795 95
0.30 1365 385 1195 275 1085 220 815 115 750 105
0.40 1325 385 1170 290 1045 230 770 130 700 110
0.50 1245 370 1130 300 1010 240 720 135 660 120
0.60 1180 360 1095 305 970 245 675 140 605 125
0.70 N/A N/A 1045 310 935 255 615 150 560 130
0.80 N/A N/A 1000 290 895 260 580 155 505 135
BLOWER DATA
ML196DF090XE48C PERFORMANCE (Less Filter)
External
Static
Pressure
in. w.g.
Air Volume / Watts at Various Blower Speeds
High Medium-High Medium Medium-Low Low
cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts
0.00 1760 435 1555 280 1405 230 1315 175 1190 135
0.10 1730 445 1515 300 1375 240 1280 190 1150 145
0.20 1700 455 1475 315 1350 250 1245 205 1115 155
0.30 1670 465 1445 330 1310 265 1200 220 1070 165
0.40 1640 480 1410 340 1265 275 1160 230 1025 175
0.50 1590 485 1380 345 1225 285 1125 235 985 185
0.60 1530 465 1340 360 1195 295 1085 245 945 195
0.70 N/A N/A 1315 370 1150 305 1065 255 895 200
0.80 N/A N/A 1280 375 1115 315 1015 265 860 210
ML196DF110XE60C PERFORMANCE (Less Filter)
External
Static
Pressure
in. w.g.
Air Volume / Watts at Various Blower Speeds
High Medium-High Medium Medium-Low Low
cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts
0.00 3115 669 1895 466 1710 356 1605 285 1415 209
0.10 2090 686 1845 476 1670 368 1570 299 1380 217
0.20 2060 701 1790 487 1630 375 1520 315 1320 222
0.30 2020 711 1760 498 1590 393 1470 324 1280 236
0.40 1980 734 1715 511 1545 403 1420 342 1220 247
0.50 1935 740 1690 525 1500 418 1370 347 1170 264
0.60 1895 749 1625 536 1460 423 1335 358 1110 269
0.70 1830 738 1600 548 1410 438 1280 367 1080 286
0.80 1765 723 1550 564 1370 456 1240 387 1010 290

Page 5
FIGURE 1
CONTROL BOX
(Includes integrated control,
transformer, circuit breaker and door switch)
BAG ASSEMBLY
(shipping location)
BLOWER MOTOR
(hidden)
BURNER
ACCESS
PANEL
COMBUSTION
AIR INDUCER
BURNER BOX ASSEMBLY
(includes sensor, rollout switches and ignitor) GAS VALVE
BLOWER DECK
COLD END HEADER BOX
PRIMARY LIMIT
DuralokPlusTM
HEAT EXCHANGER
ASSEMBLY
COMBUSTION AIR INDUCER
PRESSURE SWITCH
PARTS ARRANGEMENT
BLOWER
ACCESS
PANEL

Page 6
I-UNIT COMPONENTS
ELECTROSTATIC DISCHARGE (ESD)
Precautions and Procedures
CAUTION
Electrostatic discharge can affect elec
tronic components. Take precautions
to neutralize electrostatic charge by
touching your hand and tools to metal
prior to handling the control.
ML196DFE unit components are shown in figure 1. The
combustion air inducer, gas valve and burners can be ac
cessed by removing the outer access panel. The blower
and control box can be accessed by removing the blow
er access panel.
A-Control Box Components (Figure 2)
Unit transformer (T1) and integrated ignition control (A92)
are located in the control box. In addition, a door interlock
switch (S51) is located in the control box.
FIGURE 2
DOOR INTERLOCK
SWITCH (S51)
INTEGRATED IGNITION
CONTROL
(A92)
TRANSFORMER
(T1)
ML196DFE Control
Box
CIRCUIT
BREAKER
(CB8)
1. Transformer (T1)
A transformer located in the control box provides power to
the low voltage section of the unit. The transformers on all
models are rated at 40VA with a 120V primary and 24V
secondary.
2. Door Interlock Switch (S51)
A door interlock switch rated 14A at 120VAC is located on
the control box. The switch is wired in series with line volt
age. When the blower door is removed the unit will shut
down.
3. Circuit Breaker (CB8)
A 24V circuit breaker is also located in the control box. The
switch provides overcurrent protection to the transformer
(T1). The breaker is rated at 3A at 32V. If the current ex
ceeds this limit the breaker will trip and all unit operation will
shutdown. The breaker can be manually reset by pressing
the button on the face.
4. Integrated Ignition Control (A92)
WARNING
Shock hazard.
Disconnect power before servicing. Control is not
field repairable. If control is inoperable, simply re
place entire control.
Can cause injury or death. Unsafe operation will
result if repair is attempted.
The hot surface ignition control system consisting of an in
tegrated control (figure 3 with control terminal designa
tions in tables 1, 2 and 3), sensor and ignitor (figure 5). The
integrated control and ignitor work in combination to en
sure furnace ignition and ignitor durability. The integrated
control, controls all major furnace operations. The inte
grated control also features a RED LED for troubleshoot
ing and two accessory terminals rated at (1) one amp. See
table 4 for troubleshooting diagnostic codes. The nitride
ignitor is made from a non-porous, high strength propri
etary ceramic material that provides long life and trouble
free maintenance.
TABLE 1
4-Pin Terminal Designation
PIN # FUNCTION
1Combustion Air Inducer Line
2Ignitor Line
3Combustion Air Inducer Neutral
4Ignitor Neutral
TABLE 2
12-Pin Terminal Designations
PIN # FUNCTION
1High Limit Output
2Not Used
324V Line
4Not Used
5Rollout Switch Out
624V Neutral
7High Limit Input
8 Ground
9Gas Valve Common
10 Pressure Switch In
11 Rollout Switch In
12 Gas Valve Out

Page 7
TABLE 3
1/4” QUICK CONNECT TERMINALS
120HUM Humidifier 120VAC
LINE 120VAC
XFMR Transformer 120VAC
CIRC Indoor blower 120VAC
EAC Indoor air quality accessory 120VAC
NEUTRALS Common 120VAC
HUM24 Humidifier 24VAC
3/16” QUICK CONNECT TERMINALS
COOL Cooling tap 24VAC
HEAT Heating tap 24VAC
FAN Continuous blower 24 VAC
PARK (no power) Park terminal for unused speed taps
FS Flame sense
24 COM Common 24VAC
TABLE 4
The integrated control is equipped with an LED light for troubleshooting. The diagnostic codes are listed below in table 4.
RED LED
Flash Code 2Diagnostic Codes / Status of Furnace
Off No power to control or board fault detected
Heartbeat
1
Normal Operation - Idle, Continuous Fan, Cool
Continuous Rapid
Flash Call For Heat / Burner Operation
1Reverse Line Voltage Polarity
2Improper Earth Ground
3Burner failed to light, or lost flame during heat demand
4Low Flame Signal - check flame sensor
5Watchguard - burner failed to light, exceeded maximum number of retries or recycles.
6Not Used
7Primary or Secondary Limit Open or Watchguard Mode - Limit Switch Open longer than 3 min
utes
8Rollout Switch Open
9Pressure Switch failed to close or opened during heat demand
10 Watchguard - Pressure Switch opened 5 times during one heat demand
11 Pressure Switch stuck closed prior to activation of combustion air inducer
12 Flame Sensed without gas valve energized
13 Low Line Voltage
Notes
Note 1 A ”Heartbeat” is indicated by a ”Slow Flash” - 1 sec on 1 sec off, repeating
Note 2 Error codes are indicated by a ”Rapid Flash” - the LED flashes X times at 1/2 sec on 1/2 sec
off, remains off for 3 sec, then repeats
Note 3
Last 10 error codes are stored in memory including when power is shut off to the unit. - To recall,
press and release button, most recent will be displayed first, LED off for 3 sec, then next error
code is displayed, etc. To clear error codes, depress and hold button longer than 5 seconds.

Page 8
FIGURE 3
INTEGRATED CONTROL
(Automatic Hot Surface Ignition System)
BLOWER OFF DELAY
RED LED RECALL BUTTON
Electronic Ignition
On a call for heat the integrated control monitors the com
bustion air inducer pressure switch. The control board will
not begin the heating cycle if the pressure switch is closed
(by-passed). Once the pressure switch is determined to be
open, the combustion air inducer is energized. When the
differential in the pressure switch is great enough, the pres
sure switch closes and a 15-second pre-purge begins. If
the pressure switch is not proven within 2-1/2 minutes, the
integrated control goes into Watchguard-Pressure Switch
mode for a 5-minute re-set period.
After the 15-second pre-purge period, the ignitor warms up
for 20 seconds during which the gas valve opens at 19 sec
onds for a 4-second trial for ignition. The ignitor remains
energized for the first 3 seconds during the 4 second trial. If
ignition is not proved during the 4-second period, the inte
grated control will try four more times with an inter purge
and warm-up time between trials of 35 seconds.
After a total of five trials for ignition (including the initial
trial), the integrated control goes into Watchguard-Flame
Failure mode. After a 60-minute reset period, the inte
grated control will begin the ignition sequence again.
Fan Time Control
Heating Fan On Time
The fan on time of 30 seconds is not adjustable.
Heating Fan Off Time
Fan off time (time that the blower operates after the heat
demand has been satisfied) can be adjusted by moving the
jumper to a different setting. The unit is shipped with a fac
tory fan off setting of 90 seconds. For customized comfort,
monitor the supply air temperature once the heat demand
is satisfied. Note the supply air temperature at the instant
the blower is de-energized.
Adjust the fan-off delay to achieve a supply air temperature
between 90° - 110° at the instant the blower is de-ener
gized. (Longer delay times allow for lower air temperature,
shorter delay times allow for higher air temperature). See
figure 4.
Cooling Fan On Time
The fan on time is 2 seconds and is not adjustable.
Cooling Fan Off Time
The control has a 45 second fan off delay after cooling de
mand has been met. This delay is factory set and not ad
justable.
HEAT FAN‐OFF TIME IN SECONDS
To adjust fan-off timing, reposition jumper across pins to
achieve desired setting.
NO JUMPER
FIGURE 4
60 90
120
180
60 90
120
180
60 90
120
180
60 90
120
180
60 Second
off Time
90 Second
off Time
120 Second
off Time
180 Second
off Time

Page 9
FIGURE 5
ML196DFE Burner Box Assembly
SENSOR
ROLLOUT SWITCHES
GAS VALVE
IGNITOR
BURNERS
FRONT BURNER BOX PLATE
B-Heating Components
Combustion air inducer (B6), primary limit control (S10),
SureLight ignitor, burners, flame rollout switch (S47), gas
valve (GV1), combustion air prove switch (S18), and clam
shell heat exchangers are located in the heating compart
ment. The heating compartment can be accessed by re
moving the outer access panel.
1. Flame Rollout Switches (Figure 5)
Flame rollout switches S47 are SPST N.C. high temperature
limits located on the top left and bottom right of the front buner
box plate. S47 is wired to the burner ignition control A92.
When either of the switches sense flame rollout (indicat
ing a blockage in the combustion passages), the flame
rollout switch trips, and the ignition control immediately
closes the gas valve. Switch S47 in all ML196DFE units is
factory preset to open at 210_F + 12_F (99_C + 6.7_C) on a
temperature rise. All flame rollout switches are manual reset.
See table 4 flash code 8 for troubleshooting.
2. Heat Exchanger (Figure 6)
ML196DFE units use an aluminized steel primary and
stainless steel secondary heat exchanger assembly.
Heat is transferred to the air stream from all surfaces of
the heat exchanger. The shape of the heat exchanger en
sures maximum efficiency.
The combustion air inducer pulls fresh air through the burn
er box. This air is mixed with gas in the burners. The gas /
air mixture is then burned at the entrance of each clam
shell. Combustion gases are then pulled through the primary
and secondary heat exchangers and exhausted out the ex
haust vent pipe.
3. Primary Limit Control (Figure 6)
Primary limit (S10) used on ML196DFE units is located in the
heating vestibule panel. When excess heat is sensed in the
heat exchanger, the limit will open. Once the limit opens, the
furnace control energizes the supply air blower and de-en
ergizes the gas valve. The limit automatically resets when
unit temperature returns to normal. The switch is factory
set and cannot be adjusted. For limit replacement remove
wires from limit terminals and rotate limit switch 90 de
grees. Slowly remove from the vestibule panel. Install re
placement limit with same care.

Page 10
FIGURE 6
Primary Limit Location and Heat Exchanger
Install limit face down
4. Gas Valve (GV1)
The ML196DFE uses an internally redundant to valve to as
sure safety shut‐off. If the gas valve must be replaced, the
same type valve must be used.
24VAC terminals and gas control switch are located on
top of the valve. All terminals on the gas valve are con
nected to wires from the ignition control. 24V applied to the
terminals opens the valve.
Inlet and outlet pressure taps are located on the valve. A
manifold adjustment screw is also located on the valve. An
LP/Propane changeover kit is available.
FIGURE 7
GAS VALVE SHOWN IN ON POSITION
MANIFOLD
PRESSURE
OUTLET
PORT
INLET
PRESSURE
PORT
MANIFOLD PRESSURE
ADJUSTMENT SCREW
(under barbed fitting)
5. Flame Sensor (Figure 5)
A flame sensor is located on the left side of the burner sup
port. The sensor is mounted on the bottom burner box plate
and the tip protrudes into the flame envelope of the left-
most burner. The sensor can be removed for service with
out removing any part of the burners. During operation,
flame is sensed by current passed through the flame and
sensing electrode. The ignition control allows the gas valve
to remain open as long as flame signal is sensed.
NOTE - The ML196DFE is polarity sensitive. Make sure
that the furnace is wired correctly and is properly grounded.
A microamp DC meter is needed to check the flame signal
on the integrated control.
Flame (microamp) signal is an electrical current which passes
from the integrated control to the sensor during unit operation.
Current passes from the sensor through the flame to ground to
complete a safety circuit.
To Measure Flame Signal - Integrated Control:
Use a digital readout meter capable of reading DC micro
amps. See figure 8 for flame signal check.
1 - Set the meter to the DC amps scale.
2 - Turn off supply voltage to control.
3 - Remove sensor wire from integrated control.
4 - Connect (-) lead to flame sensor wire.
5 - Connect (+) lead to Terminal FS on integrated control.
6 - Turn supply voltage on and close thermostat contacts to
cycle system.
7 - When main burners are in operation for two minutes, take
reading.
6. Ignitor (Figure 5)
ML196DFE units use a mini-nitride ignitor made from a pro
prietary ceramic material. To check ignitor, measure its re
sistance and voltage. A value of 39 to 70 ohms indicates a
good ignitor. Voltage to the ignitor should be 102VAC -
132VAC. See figure 9 for resistance and voltage checks.